Use of a protection layer to protect a passivation while etching a wafer

Abstract

A method for processing a wafer in accordance with various embodiments may include: forming a passivation over the wafer; forming a protection layer over at least a surface of the passivation facing away from the wafer, wherein the protection layer includes a material that is selectively etchable to a material of the passivation; forming a mask layer over at least a surface of the protection layer facing away from the wafer, wherein the mask layer includes a material that is selectively etchable to the material of the protection layer; etching the wafer using the mask layer as a mask; selectively etching the material of the mask layer to remove the mask layer from the protection layer, after etching the wafer; and selectively etching the material of the protection layer to remove the protection layer from the passivation, after selectively etching the material of the mask layer.

What is claimed is: 
     
       1. A method for processing a wafer, the method comprising:
 forming a passivation over the wafer; 
 forming a protection layer over at least a surface of the passivation facing away from the wafer, wherein the protection layer comprises a material that is selectively etchable to a material of the passivation; 
 forming a mask layer over at least a surface of the protection layer facing away from the wafer, wherein the mask layer comprises a material that is selectively etchable to the material of the protection layer; 
 etching the wafer using the mask layer as a mask; 
 selectively etching the material of the mask layer to remove the mask layer from the protection layer, after etching the wafer; 
 selectively etching the material of the protection layer to remove the protection layer from the passivation, after selectively etching the material of the mask layer; and 
 disposing chip packaging material on the passivation after selectively etching the material of the protection layer. 
 
     
     
       2. The method according to  claim 1 ,
 wherein forming the passivation over the wafer comprises forming the passivation over a front side of the wafer. 
 
     
     
       3. The method according to  claim 1 ,
 etching the wafer using the mask layer as a mask comprises plasma etching the wafer using the mask layer as a mask. 
 
     
     
       4. The method according to  claim 3 ,
 wherein plasma etching the wafer comprises a Bosch plasma etch process. 
 
     
     
       5. The method according to  claim 1 ,
 wherein the material of the protection layer is further selectively etchable to the material of the mask layer. 
 
     
     
       6. The method according to  claim 1 ,
 wherein the material of the passivation is selected from a group of materials, the group consisting of: 
 an epoxy material; 
 an imide material; 
 a polyimide material; and 
 benzocyclobutene. 
 
     
     
       7. The method according to  claim 1 , wherein the material of the protection layer is selected from a group of materials, the group consisting of:
 silicon nitride; 
 carbon; 
 carbon containing nitrogen; 
 silicon containing carbon; 
 polysilicon; and 
 a resist material. 
 
     
     
       8. The method according to  claim 1 , wherein the material of the mask layer is selected from a group of materials, the group consisting of:
 a resist material; 
 an imide material; 
 a polyimide material; 
 an epoxy material; 
 benzocyclobutene. 
 
     
     
       9. The method according to  claim 1 ,
 wherein etching the wafer comprises dicing the wafer. 
 
     
     
       10. The method according to  claim 1 , wherein the protection layer has a thickness in the range from about 20 nanometers to about 2000 nanometers. 
     
     
       11. The method according to  claim 1 , wherein selectively etching the material of the protection layer to remove the protection layer from the passivation comprises a plasma etch process. 
     
     
       12. A method for processing a wafer, the method comprising:
 forming a passivation over the wafer; 
 forming a protection layer over at least a surface of the passivation facing away from the wafer, wherein the protection layer comprises a material that is selectively etchable to a material of the passivation; 
 forming a mask layer over at least a surface of the protection layer facing away from the wafer, wherein the mask layer comprises a material that is selectively etchable to the material of the protection layer; 
 etching the wafer using the mask layer as a mask; 
 selectively etching the material of the mask layer to remove the mask layer from the protection layer, after etching the wafer; and 
 selectively etching the material of the protection layer to remove the protection layer from the passivation, after selectively etching the material of the mask layer, wherein forming the protection layer over at least the surface of the passivation facing away from the wafer comprises: 
 forming the protection layer over the surface of the passivation facing away from the wafer and over at least one sidewall of the passivation. 
 
     
     
       13. The method according to  claim 12 , wherein forming the protection layer over the surface of the passivation facing away from the wafer and over at least one sidewall of the passivation comprises:
 depositing the protection layer over the surface of the passivation facing away from the wafer and over at least one sidewall of the passivation, before forming the mask layer over the surface of the protection layer facing away from the wafer; and 
 selectively etching the material of the protection layer to remove the protection layer from the at least one sidewall of the passivation, after forming the mask layer over the surface of the protection layer facing away from the wafer, and before etching the wafer. 
 
     
     
       14. The method according to  claim 13 , wherein selectively etching the material of the protection layer to remove the protection layer from the at least one sidewall of the passivation comprises a plasma etch process. 
     
     
       15. The method according to  claim 14 , wherein the plasma etch process is carried out at a temperature in the range from about 10° C. to about 150° C. 
     
     
       16. The method according to  claim 13 , wherein selectively etching the material of the protection layer to remove the protection layer from the at least one sidewall of the passivation comprises using a CF 4 /O 2  process gas mixture. 
     
     
       17. The method according to  claim 12 , wherein forming the mask layer over at least the surface of the protection layer facing away from the wafer comprises forming the mask layer over the surface of the protection layer facing away from the wafer and at least one sidewall of the protection layer. 
     
     
       18. A method for processing a wafer, the method comprising:
 forming a passivation over the wafer; 
 forming a protection layer over at least a surface of the passivation facing away from the wafer, wherein the protection layer comprises a material that is selectively etchable to a material of the passivation; 
 forming a mask layer over at least a surface of the protection layer facing away from the wafer, wherein the mask layer comprises a material that is selectively etchable to the material of the protection layer; 
 etching the wafer using the mask layer as a mask; 
 selectively etching the material of the mask layer to remove the mask layer from the protection layer, after etching the wafer; and 
 selectively etching the material of the protection layer to remove the protection layer from the passivation, after selectively etching the material of the mask layer, wherein the material of the passivation comprises an imide material, wherein the material of the protection layer comprises silicon nitride, and wherein the material of the mask layer comprises a photoresist. 
 
     
     
       19. A method for processing a wafer, the method comprising:
 forming a passivation over the wafer; 
 forming a protection layer over at least a surface of the passivation facing away from the wafer, wherein the protection layer comprises a material that is selectively etchable to a material of the passivation; 
 forming a mask layer over at least a surface of the protection layer facing away from the wafer, wherein the mask layer comprises a material that is selectively etchable to the material of the protection layer; 
 etching the wafer using the mask layer as a mask; 
 selectively etching the material of the mask layer to remove the mask layer from the protection layer, after etching the wafer; and 
 selectively etching the material of the protection layer to remove the protection layer from the passivation, after selectively etching the material of the mask layer, wherein the material of the protection layer comprises a positive photoresist and the material of the mask layer comprises a negative photoresist, or vice versa.